1. Field of the Invention
The present invention relates to a bit map data generation apparatus for generating bit map data which is particularly suitable for a serial printer-using a wire dot type recording head, from an outline font, and more particularly to a technique of a half-dot protect process.
2. Prior Art
In an outline font, data indicative of a character or a figure are stored in the form of its contour line. Since the amount of the data is much smaller than that of bit map data, an outline font is widely used in a printer which requires a high print quality.
Such an outline font should be once converted into bit map data during a printing process. Especially, in a wire dot type recording head, a high-speed operation can be attained by printing only every other dot of adjoining dots in the row direction. Therefore, it is necessary to perform a half-dot protect process to thin out the data in which every other bit in the row direction is surpassed from being printed.
In such a process, generally, every other dot is mechanically thinned out by a logical circuit. This gives rise to a problem in the case wherein an even number of dots adjoin one another in the row direction. Namely, among dots constituting a character or pattern, dots in the contour portion are thinned out as shown in FIGS. 9(A) and 9(B), with the result that the contour of the printed character or pattern is unclear.